Quinton's Father Had an Irrational Fear of Railroad Crossings and Would

Quinton's father had an irrational fear of railroad crossings and would sometimes spend hours planning family trips so that all railroad crossings were avoided. Which of the following processes would best explain the acquisition of his phobia if Quinton also develops a fear of railroad crossings?

A) reciprocal stress
B) observational learning
C) classical conditioning
D) operant conditioning